occu - oper
- occupant
- occupation authority
- occupational disease
- occupational hazard
- occupational level
- occupational standards
- occupier
- occur
- occurrence
- occurrence cause
- occurrence circumstances
- occurrence location
- occurrence probability
- occurrence to touch-down
- ocean floor
- ocean station
- ocean station vessel
- ocean-dedicated satellite
- oceanic area control center
- oceanic control area
- oceanic environment
- oceanographic satellite
- oceanography
- oceanological spacecraft
- oceanology
- octane
- octane improvement
- octane number
- octane number response
- octane promoter
- octane rating
- octane scale
- octane unit
- octane value
- octant
- octantal deviation
- octave band filter
- octave-band center frequency
- odor removal
- OEM supplier
